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Stellarator

A stellarator is a device that uses external magnetic coils to confine plasma. Unlike tokamaks, stellarators do not require a plasma current for confinement.

Definition

Section titled “Definition”

A stellarator is a magnetic confinement fusion device that creates a twisted toroidal magnetic field using only external coils. The name was coined by Lyman Spitzer at Princeton in 1951, derived from “stellar” (relating to stars) and “generator.”

How It Works

Section titled “How It Works”
  1. Complex, twisted external coils generate the entire magnetic field
  2. The plasma follows helical magnetic field lines without needing to carry current
  3. The three-dimensional magnetic geometry provides inherent stability

Advantages

Section titled “Advantages”
  • Steady-state operation possible (no pulsed plasma current)
  • No plasma disruptions (a major tokamak concern)
  • Inherently stable magnetic configuration

Challenges

Section titled “Challenges”
  • Complex coil geometry (difficult and expensive to manufacture)
  • Historically lower confinement performance than tokamaks
  • Requires precise engineering

Examples

Section titled “Examples”
  • Wendelstein 7-X (Germany) - The world’s largest stellarator
  • Large Helical Device (Japan)
  • HSX (USA)
Section titled “Related Terms”